Every connected device has to get its data somewhere. The network decides how often a device can report, how long its battery lasts, where it can be installed and what it costs to run over its lifetime. Yet the choice is often made late, after the sensor has already been picked.
There is no single best option. This explainer compares the main families of connectivity on qualitative terms, then sets out the questions we use to choose between them on a project.
Cellular: 4G, LTE-M and NB-IoT
Standard 4G uses the public mobile network and handles larger, frequent data volumes with low delay. It suits powered devices that report often or move between sites, such as vehicle trackers, gateways and cameras. Each device needs a SIM or eSIM and a data plan, so the cost model is a recurring charge per device.
LTE-M and NB-IoT are low-power variants of mobile technology designed for IoT. They trade throughput for battery life and often reach further into buildings and basements than standard mobile data. LTE-M carries more data and supports devices on the move. NB-IoT is aimed at small, infrequent messages from devices that stay in one place, such as meters and fixed sensors.
The main limit is coverage. Availability of LTE-M and NB-IoT differs between countries and operators, so it has to be checked for each site rather than assumed.
LoRaWAN: long range, small messages, your own network
LoRaWAN is a low-power wide-area network that runs in licence-free radio bands. Battery-powered sensors send short messages to gateways, which pass them to a network server over the internet. A single gateway can cover a wide area such as fields, a car park or a campus, and batteries can last a long time because devices transmit briefly and rarely.
The cost model differs from cellular. You can run your own gateways, paying for hardware and installation once, or use a public or shared network where one exists. Messages are small and not instant, so LoRaWAN fits readings such as soil moisture, temperature, parking occupancy or tank levels, not video or continuous streams. Licence-free bands also come with rules on how often a device may transmit.
Wi-Fi and Ethernet: when the site already has a network
Inside buildings with existing infrastructure, Wi-Fi and Ethernet are often the simplest route. They carry large data volumes with low delay and no per-device airtime charge. Ethernet is the most dependable choice for fixed equipment such as controllers, meters in plant rooms and chargers, and it can also supply power over the same cable.
Wi-Fi draws more power than the low-power options, so it suits mains-powered devices. On a customer's network it also raises questions the IoT team does not control: password changes, firewall rules, and who is responsible when a device drops off. Agree these with the IT team at the start.
Bluetooth LE: short range, very low power
Bluetooth Low Energy connects devices over short distances using very little power. It is common for tags, beacons, wearables and sensors that talk to a nearby phone, gateway or tracker rather than to the internet directly. In a vehicle, for example, a wireless sensor can report to an on-board tracker, which forwards the data over the mobile network.
Range is limited, and walls, metal and people reduce it further. Bluetooth LE is therefore usually one link in a chain, not the whole path.
How the options compare
- Range: Bluetooth LE covers a room or a vehicle, Wi-Fi a building, LoRaWAN a site or wider area from one gateway, and cellular wherever the operator has coverage.
- Power: Bluetooth LE, LoRaWAN, LTE-M and NB-IoT suit battery devices; standard 4G, Wi-Fi and Ethernet usually need a power supply.
- Data volume: 4G, Wi-Fi and Ethernet handle large and frequent data; LTE-M handles moderate volumes; NB-IoT and LoRaWAN are built for small messages.
- Cost model: cellular usually means a recurring plan per device; LoRaWAN means gateway hardware or a network subscription; Wi-Fi and Ethernet reuse infrastructure the site already has.
- Indoor and underground: NB-IoT and LTE-M often reach further indoors than standard mobile data, and LoRaWAN gateways can be placed where they are needed, but basements and underground car parks still need a survey.
Questions to ask before choosing
- How often must the device report, and how quickly must a reading reach someone?
- Is there mains power, or must the device run on a battery for years?
- Does the device move between sites, or stay in one place?
- What coverage exists at the actual installation points, including basements, metal enclosures and remote fields?
- Who will own and maintain the network: you, a mobile operator or the IT team on site?
- What happens when the connection drops, and can the device store readings and send them later?
Many systems combine networks: Bluetooth LE sensors reporting to a gateway, the gateway connected over Ethernet or cellular, and a second path for when the first one fails. A LIOMO project typically starts with this assessment, then selects hardware and connectivity to suit the site, rather than fitting the site to a favourite technology.